Pouring spout



Nov. 8, 1960 M. TAMA ETAL 2,959,757

POURING sPouT Filed July l0, 1958 4 Sheets-Sheet 2 INVENTORS 4M/o TAMA ywa aux f. J//fA/Pm/v BY l, QQ

Nov. 8, 1960 M. TAMA ETAL POURING SPOUT 4 Sheets-Sheet 3 Filed July lO.1958 ORNEYS Nov. 8, 1960 M. TAMA ETAL POURING sPoUT 4 sheets-sheet 4Filed July 10. 1958 lwm.

BY e @n A9 QSL I oRNEYs United Statesg Patent Chloe.

2,959,757 Patented Nov. s, 1960 PURING SPOUT Mario Tama, Morrisville,and Wilbur E. Shearman,

Yardley, Pa., assgnors to Ajax Magnethermic Corporation, Trenton, NJ., acorporation of Ohio Filed July 1o, 195s, ser. No. 747,667

' 12 claims. (ci. sas-24s) The present invention relates to pouringconduits for molten metal and the like and particularly to pouringspouts for furnaces.

This application has been divided and the subject matter relating to thefurnace has been embodied in divisional application Serial No. 37,457,filed June 20, 1960, for Furnace.

A purpose of the invention is to permit extension of the pouring spoutwell out beyond the furnace so that it can pour directly tothe locationat which the molten metal or the like is to be used.

A further purpose is to reduce the danger of damage to electric heatersby penetration of molten metal around the resistor elements whichsurround a conduit for molten metal.

A further purpose is to provide a flange which may take the shape of aflare or cone at one or preferably both ends of a refractory heater tubeand to extend the flange outwardly so as to reduce the possibility thatmolten metal can reach the resistor of the heater.

A further purpose is to employ a flanged heater tube ofsilicon-nitride-bonded silicon carbide.

A further purpose is to effectively cool the heater tube at the endsothat any molten metal penetrating along the end and otherwise likelyto pass around the outside of the heater tube will be solidified.

A further purpose lis to employ a flange on the heater tube ofrefractory and to extend it near to the metallic casing in order toeffectively cool therefractory in that area and prevent molten metalfrom passing around the heater tube.

A further purpose is to secure radially extending metallic terminals inthe outside of the heater tube, preferably locking the terminals in atleast some instances intermediate the ends of the heater tube andsecuring the resistors to the terminals.

A further purpose is to create multiple heating zones of controlledtemperatures in a molten metal conduit.

Further purposes appear in the specification and in the claims.

In the drawings we have chosen to illustrate a few only of the numerousembodiments in which the invention may appear, selecting the forms shownfrom the standpoints of convenience in illustration, satisfactoryoperation and clear demonstration of the principles involved.

Figure 1 is a central vertical diagrammatic section of an electricinduction furnace to which the invention has been applied.

Figure 2 is an enlarged side elevation of the pouring spout, partiallysectioned away.

Figure 3 is a fragmentary section on the line 3-3 of Figure 2.

Figure 4 is a fragmentary section on the line 4 4 of Figure 2.

Figure 5 is a section lthrough the axis of the pouring spout of Figure2.

Figure 6 is an enlarged fragment of Figure 5.

Figure 7 is a fragmentary section on the line 7-7 of Figure 5.

Figure 8 is a top plan view of a modified form of heater tube accordingto the invention, broken away to show one of the terminal sockets.

Figure 9 is a side elevation of the heater tube of Figure 8, broken awayto show one of the turn-around pin sockets.

Figure 10 is a left end elevation of the heater tube of Figures 8 and 9.

Figure 1l is an enlarged fragmentary axial section of the heater tube ofFigures 8 to 10.

Figure l2 is an axial section of a launder in accordance with theinvention.

Figure 13 is an enlarged fragmentary axial section of the launder ofFigure l2.

Figure 14 is an axial lsection of a modified form of launder accordingto the invention.

Figure 15 is an enlarged fragmentary axial section of the launder ofFigure 14.

Describing in illustration but not in limitation and referring to thedrawings.

In the prior art, difficulty has been encountered in producingelectrically heated pouring spouts, launders and other conduits to beused in connection with melting furnaces for metal and the like, due tothe tendency of molten metal from the charge to penetrate through oraround the heater tube and short circuit the electric resistor elements.This seepage of molten metal has been due to formation of cracks in theinner refractory tube.

In the prior art in many cases the heater support tube, called hereinthe heater tube, was of metal and had very little resistance againstmolten metal attack.

In accordance with the present invention, an improved construction ofpouring spout or other conduit for molten metal provided with anelectric heater has been produced.

In accordance with the invention, the heater tube is made of refractory,and for best results, silicon carbide bonded with silicon nitride hasbeen employed, which has the following remarkable combination ofproperties:

(l) The heat conductivity is as high as that of silicon carbide.

(2) The refractory is very resistant to penetration of molten metalsgenerally and particularly to penetration of molten aluminum, to whichthe invention is particularly applicable.

(3) The mechanical strength of the refractory is about three times ashigh as that of silicon carbide.

(4) It is adequately resistant to variation in temperature, so thatspalling and similar difficulties are not likely to occur.

In accordance with the invention, the heater tube at the end nearest thefurnace and preferably at both ends is provided with an integral flangewhich may take the shape of a flare or cone and which extends outwardlypreferably to a position near the metallic casing. No heater elementssurround this flange, and therefore the outer edge of the flange assumesa temperature well below the melting point of the metal in the conduit.The flange physically acts as a dam or `obstruction to prevent moltenmetal from entering the `region of the electric resistor elements, andit also acts as a cooling lin to maintain a temperature low enough sothat any molten metal entering this area will solidify. In order to passaround the heater tube, the molten metal would have to flow out aroundthe flange and then inwardly into contact with the heater elements, andthis is very unlikely to occur. At the discharge end the heater tube isdesirably carried' alm-ost to the point at which the molten metaldischarges so that there is little danger that molten metal could passaround the heater tube at that end.

The device of the invention desirably incorporates metallic terminalswhich are mounted in sockets in the heater tube, the feeder terminals inthe preferred ernbodiment being located at the middle of the heater tubeso as to be well protected from contact with molten metal.

The invention is applicable to any conduit which carries molten metalfrom one furnace to another, or from a furnace to a casting mechanism orthe like. The invention is particularly applicable to pouring spoutswhich convey molten metal from a melting furnace or otherwise to a diecasting machine such as a cold chamber die casting machine.

`Considering first the form of Figures' l to 7, we illustrate anelectric induction furnace 20 having a furnace chamber 21 and asubmerged channel 22. The submerged channel has within it one leg of acore type transformer core 23 which -is surrounded with a furnaceinductor coil 24.

The furnace chamber has a refractory lining 25 and the submerged channelhas a refractory lining 26. Around the refractory lining heat insulationis provided at 27 and the entire furnace is supported by a metalliccasing 28. A removable plug `30 is provided at the bottom of the channelfor clean-out purposes.

At the top the furnace chamber is covered by a gas tight refractorycover 31 having a metallic casing 32 and removably secured by fastenings33. There is also a refractory inlet opening provided at 34 closed by asuitable gas tight cover 35.

At the outlet end, the furnace has a discharge opening 36 through therefractory which connects to the lower and inner end of a pouring spout37 which discharges to a suitable mechanism, in this case a cold chamberdie casting machine 38. Discharge is accomplished by maintaining apositive pressure from a suitable gas such as air, nitrogen, or carbonmonoxide introduced through an opening 40 in measured quantities tocontrol the discharge as known in the art.

The pouring spout 37 has a tubular metallic casing 41 which is securedas by welding to a welded metallic housing 42 which is united as bywelding to a spout base plate 43 which is suitably secured to themetallic furnace casing as by bolts passing through openings `44. Themounting plate has a suitable opening through which the refractoryextends as later explained.

Within and surrounding the casing 41 of the spout is a heat insulatinglining 45 suitably of asbestos within which is placed the refractoryheater tube 46 to be described, whieh has wound thereon metallicresistor elements 47 of any suitable material, such as Nichrome.

Within the heater tube and desirably iltting the inner wall of theheater tube is placed the tubular refractory spout lining 48 which hasan interior passage 50 connecting to the outlet opening 36 of thefurnace and reducing in cross section to an orifice 51, then enlargingat 52 and having a uniform passage 53 extending to the outer end of thespout.

The heater tube in the form of Figures l to 7 has' a generally rightcircular cylindrical portion 54 which has suitably placed spiral groovesS in the outer circumference for receiving the resistor wire. At theouter end and at the inner end of the cylindrical portion 54, there is asuitably threaded radial socket 56, best seenin Figures 5, 6 and 7,which receives a metallic turn-around pin 5S threaded on the outside andmounted in the socket. The turn-around pin has a groove at 57 in whichthe resistor wire is wrapped and supported in the form of a hairpinturn. The tum-around pin is suitably made of Nichrome or the like.

The inner ends of the two coils of resistor elements shown are receivedon terminals 60 which extend outwardly from radially threaded sockets 61near the center, best seen in Figures 3, 4 and 5. The use of twoseparate 'lli resistor elements enables separate control to the powerinput of each, thus creating multiple heating zones of controlledtemperatures. The terminals at their inner ends are threaded into thesockets and have circular recesses 62 beyond the threaded portions intowhich the ends of the respective resistors extend, the resistors beingunited by brazing or welding as desired.

The terminals 60 have outwardly extending ends 63 beyond the refractorywhich are engaged by suitable leads 64 connected thereto as by welding.The leads are suitably covered by a terminal box 65.

At the end adjoining the furnace, the heater tube has integral therewitha flange 66 which extends radially outwardly and in this form is'conical and progressively reducing in cross section toward the outerend. The flange is surrounded exteriorly by refractory heat insulation45 and inside the llange and between the ange and the inner tube 48 ofthe spout at the inner end is placed refractory cement 67.

'Fhe flange and the entire heater tube and desirably also the innerrefractory lining of the spout are produced from silicon-nitride-bondedsilicon carbide in the preferred embodiment.

In operation of the form of Figures 1 to 7 inclusive, let us' assumethat the inner refractory tube of the spout cracks or breaks, and moltenmetal penetrates outwardly. It will be impossible for such molten metalto reach the outside of the heater tube and come in contact with theelectric heating elements without passing around one end or the other ofthe heater tube, unless, of course, the heater tube itself cracks, whichis unlikely.

If the molten metal cornes to the upper end of the heater tube it willbe discharged from the spout. If the molten metal comes to the lower endof the heater tube, which it is more likely to do under the action ofgravity, the molten metal cannot flow around the outside of the heatertube without flowing outwardly along the flange 66. But since the flange66 extends well out toward the outside of the spout and extends close tothe metallic housing 42 and the metallic casing 41, the molten metal islikely to solidify and cease to ilow so that it does not encounter theoutside of the heater tube and does not engage and short circuit theresistors.

In the embodiment shown in Figures l to 7, heat is concentrated at thelower end and the upper end of the spout by placing the resistors closetogether at 68 and 70 and spacing them more widely in between at 71. Theterminals connected to the power leads are remote from the hotter partsof the heater tube.

In Figures 8 to 10 we illustrate a modied form of heater tube, suitablefor use in a pouring spout as shown in Figures l to 7.

In this case the heater tube 72, desirably of siliconnitride-bondedsilicon carbide, has a cylindrical portion 73 which is provided withexternal grooves 74 to receive an electric resistor and has a ilange orflare 75 at the end adjacent the furnace which is conical andprogressively reducing in cross section toward the radial outer end. Inthis embodiment, one coil is used so that a single, continuous length ofwire forms the resistor. The ends of the wire are fixed to terminalswhich are mounted in sockets 77, with intermediate points of the wirebeing wrapped in grooves of turn-around pins mounted in sockets 76.

In this case radial sockets are provided at the ends at 76 havinginternal threads to receive threaded turnaround pins and sockets areprovided at the center at 77 which have internal threads to receiveterminals which connect to the leads from the power source as previouslyexplained.

In this form also the grooves for the resistors are placed closetogether `at the lower end 78 and the upper end 80 to concentrate theheat, and are placed more widely apart at 81 at the center.

The forms embodied in Figures 12 through 14 are desirably used where thecentral passage 85 of the launder is well below the surface of themolten metal and completely filled with molten meta-l under somepressure.

The form of Figures 12 and 13 illustrates a launder which is useful incarrying molten metal from one furnace to another or from one furnace toa casting apparatus.

In this case a refractory lining 82 and metallic casing 83 of thedischarging furnace are shown, with a discharge opening 84 through therefractory lining. The launder has a central passage 85 which is formedby a tubular refractory lining S6 desirably of silicon-nitride-bondedsilicon carbide made in sections which have cooperating groove andrecess connections 87 at the ends. The inner refractory tubes 86 aresurrounded by heater tubes 88 which have tubular portions in the middleand radial flanges 90 at each end. The heater tubes are desirably madeof silicon-nitride-bonded silicon carbide. Electric resistor elements 91surround the tubular portions of the heater tubes and are wired in anysuitable manner, desirably to terminals of the character alreadydescribed.

The space between the flanges of adjoining heater tubes is filled withrefractory cement at 92 and the space around the tubular portions of theheater tubes is filled with refractory heat insulation asbestos such asmagnesia 93.

The outside of the heat insulation is surrounded by a metallic casing 94which is anchored to the casing of the discharging furnace at one end inany suitable way and at the other end is anchored to the metallic casing95 of the receiving furnace which has an inlet opening 96 and arefractory lining 97.

The heater tubes and the linings of the conduit are desirably made inseveral sections to eliminate the danger of damage due to expansion andcontraction.

Figures 14 and 15 show a modified form of electrically heated launderaccording to the invention. In this case the construction is essentiallythe same as that already shown in Figures 12 and 13 except that theflanges 90 on the heater tubes are conical, instead of extendingdirectly radially outwardly. Like flanges 90 they reduce in thicknessprogressively outwardly. Refractory cement 92 is interposed inside theflanges in this form and refractory or metallic rings 98 are interposedbetween the ends of the fins as a further obstruction to flow of themolten metal outwardly.

In operation of the forms of Figures 12 to 15, it will be evident thatany molten metal which escapes through the lining of the launder mustpass around the flanges to get to the electric heater elements, and inpassing around the flanges it is subjected to the cooling effect of theflanges on the heater tubes as well as the mechanical protection whichsuch flanges give. Thus the molten metal will solidify without causingdamage.

While the invention will find application in numerous other places, itis believed to be most suitable for use with molten aluminum base alloy,magnesium base alloy, copper base alloy and zinc base alloy.

In view of our invention and disclosure, variations and modifications tomeet individual whim or particular need will doubtless become evident toothers skilled in the art, to obtain all or part of the benefits of ourinvention without copying the structure and method shown, and we,therefore, claim all such insofar as they fall within the reasonablespirit and scope of our claims.

Having thus described our invention, what we claim as new and desire tosecure by Letters Patent is:

1. In a spout or conduit for molten metal, a refractory element having aconduit opening, a refractory heater tube surrounding the refractoryelement, the heater tube having a flange extending outwardly at one end,the flange tapering in thickness from its shortest radius to its longestradius, and an electric heater around the heater tube.

2. In a conduit for molten metal or the like, a refractory elementhaving a conduit opening thereto, a refractory heater tube surroundingthe refractory element and having an outwardly extending flange at eachend, the

6 flanges tapering in thickness from their shortest radius to theirlongest radius, and an electric heater element surrounding the heatertube.

3. In a conduit for molten metal, a refractory element having a conduitopening therethrough, a refractory heater tube surrounding therefractory element and having an outwardly flaring flange at one end,the flange tapering in thickness from its radially inner end to itsradially outer end, refractory filling the space between the refractoryelement and the flaring flange, and an electric heater surrounding theheater tube.

4. In a conduit for molten metal, a refractory element having a conduitopening therethrough, a successtion of refractory heater tubessurrounding the refractory element and each having at the ends thereofoutwardly extending flanges, the flanges tapering in thickness fromtheir shortest radius to their longest radius, and electric heaterssurrounding the heater tubes.

5. In a conduit for molten metal, a refractory element having a conduitopening therethrough, a refractory heater tube surrounding therefractory element and having an outwardly extending flange at one end,the flange tapering in thickness from its shortest radius to its longestradius, an electric heater surrounding the heater tube, a metalliccasing surrounding the heater tube and being closer to the flangeportion than to the other parts of the heater tube, and heat insulationin the space between the metallic casing and the heater tube.

6. In a conduit for molten metal, a refractory element having an openingtherethrough, a refractory heater tube surrounding the refractoryelement, and having outwardly extending openings intermediate the ends,metallic terminals secured in the openings and extending outwardly, anelectric heater connected to the terminals and surrounding the heatertube and heat insulation surrounding the heater and the heater tube andamong the terminals.

7. A conduit of claim 6, in which the heater tube has a flange at oneend.

8. An electric resistance heater tube, composed of refractory materialand comprising a cylindrical body and a radially outwardly extendingflange at one end.

9. A tube of claim 8, in which the flange tapers in thickness from itsshortest radius to its longest radius.

10. An electric resistance heater tube, composed ofsilicon-nitride-bonded silicon carbide, having a cylindrical body, andhaving a radially outwardly extending flange at one end of the body, theflange tapering in thickness from its shortest radius to its longestradius.

11. An electric resistance heater tube, composed ofsilicon-nitride-bonded silicon carbide, having a cylindrical portion andhaving grooves in the outside of the cylindrical portion.

12. A heater tube of claim 11, having a radially outwardly extendingflange at one end thereof, the flange tapering in thickness from itsshortest radius to its longest radius.

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